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electrics problem

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bosun:
Hi Guys ,
Can anyone help me out with this problem,,I am trying to set up the electrics in a model of an ocean going steam tug, that is 44 inches long by 13 inchers beam so it is quite big.. I am using an Acoms 2 channel Tx to an Acoms Rx, bought complete and new. I have installed a 550 motor running on 6 volts going to a 6omm prop, so far so good. When I push the forward control lever on a bench test  the prop rotates ok, when it reaches halfway it slows down and gets a bit erratic, When I pull the lever to go astern there is no response,  I have tried various battery set ups from 6 volt , 7.2. through to 12, it is the same, I have put the rudder servo into into channel 2 and it works fine, I have changed the ESC from a Ripmax Extra  that was recommended from the shop, to a Futaba, the problem is still there, and its driving me nuts . Any help would be apreciated, sorry for the long question.
Happy new Year to all.
Bosun

Telstar:
Hi Bosun,
Happy New Year.
With your problem, are you using BEC to power your receiver or a separate battery (or inadvertently both)
I would take the Rx and battery out on to the bench (a different motor saves removing the one in the tug) and rig it up to test. If you are using a Rx battery separate, you should have disabled the BEC on the ESC, I do this by disconnecting the red wire between the Rx and ESC. Asking the obvious are you setting up with the throttle in the mid travel on your Tx (some ESC's self set on switch on)
If you think I can help send me a PM
luck Tom

FullLeatherJacket:
Bosun
It might be the ESC which isn't suitable. Check the type you have against this table; some don't have a reverse while others have the facility to disable it.
http://www.futaba-rc.com/radioaccys/old-speed-controls.html
On another tack, are you using a geared motor? A 550 on direct drive to a 60mm prop sounds a bit heavy-going for the motor in a big model like this one. Anyone else have any experience of such a set-up?

Doc:
Bosun,
First, does your ESC have a reverse to start with?  Dumb question, but I've done things 'dumber'.
Then, check the current handling capacity of the ESC as compared to the motor.  If the ESC's ratings aren't higher than the motor's, that would be the problem, I'd think.
And then, the 'start up' procedure (if any).  Throttle at 'neutral' at 'turn on', and then it depends on the ESC.
And check all the wiring/connections.  Anything getting sort of 'warm-ish'?  And are the connectors tight?
[Used some of the 'bullet' type connectors with a plastic 'sleeve' that covered the connection when connected.  Didn't pay enough attention and 'thought' it was connected when it actually wasn't (sleeve was harder to make slip on than I thought).  Things fine till the plastic sleeve heated up a bit, expanded, broke the connection.  When it cooled it contracted, made connection, things worked fine.  The language I used would get you thrown out of any of the lowest 'dives' (bars/pubs) around here!]
Good luck!
 - 'Doc

bosun:
Hy Guys.
 Thanks for the quick replies to the electrics problem, to be honest it has restored my faith in the modelling community, I was ready to pack it all in before I had even started.  I took the advice of Telstar first and did a bench test with a different motor, I had the same problem, no reverse, Then as full leather jacket suggested I had a look at the ESC ( this was the second one that I had tried) and was bought from a local model shop just before xmas, I had no reason to think that it would be the problem as the guy in the shop assured me that it was what I wanted, still I had no reverse. I then decided to take a run into Cardiff to a different model shop and buy ANOTHER esc , once again being assured that it was what I needed, I have just done another bench test and it is all working, and believe me it feels good. I have tried it in the bath, and although there is a bit of a wash, it does,nt seem to much as there is,nt any ballast in her yet,  or anything else for that matter.  I am now going to take Docs advice and spend the rest of the evening checking all the wiring and fittings.
One other things I have learned is never to take on board any advice, from some one who works in a model shop, that only stocks Cars , Hedlecopters, and Planes, but no Boats.  Once again from a complete novice to modelling many thanks.
Bosun

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